Such a medical X-ray examination apparatus is known from the scientific article “K-edge imaging in X-ray computed tomography using multi-bin photon counting detectors” (Phys. Med. Biol. 52, (2007) 4679-4696). The known medical X-ray examination apparatus is a computed tomography (CT) scanner comprising an imaging unit with a multi-bin X-ray photon counting detector. This imaging unit allows to spectrally decompose an X-ray absorption spectrum to image the X-ray absorption spectrum as a conventional X-ray absorption image and a K-edge absorption image.
The conventional X-ray absorption image is equal to the image of a conventional X-ray absorption spectrum which is acquired with an imaging unit comprising a conventional current integrating X-ray detector. The conventional X-ray absorption image includes data elements representing the anatomical background of an object of interest. The K-edge absorption image is an X-ray absorption image of material within the object of interest, said material having its K-edge absorption within the energy range of the known medical X-ray examination apparatus. The K-edge absorption image includes data elements representing quantitative information of local densities of material showing K-edge absorption within the object of interest.
The known medical X-ray examination apparatus allows selective imaging of material having its K-edge absorption in the energy range of the known medical X-ray examination apparatus, (e.g. gadolinium-based targeted contrast agents), in addition to conventional imaging of the anatomical background.
A disadvantage of the known medical X-ray examination apparatus is that the sensitivity of the selective imaging of a K-edge absorption image is relatively low. When using the known medical X-ray examination apparatus, a large number of potential clinical applications either suffer from this limited sensitivity or are completely impossible because of the low sensitivity.